So, Luka came out a few days ago. She sounds pretty good from the sample they provided. Her voice is a lot more mature, and supposedly she can sing in English better than the other vocaloids.
She sounds kinda like Len. Just my opinion there.
Scouring nico for some more samples, but I'm not finding too much that I deem good. Maybe when I do I'll post it, but I should get back to applying for college and shiz.